Lessons from the hills

Small windows to retain indoor heat, and sloped roofs with slate to drain rainwater — how architects can borrow elements from traditional mountain architecture for contemporary homes

Houses in the hills usually have a picturesque, dreamy quality, becoming one with the slopes. But hills are known for challenging climatic conditions like extreme cold, snow, and even earthquakes. There are also difficulties in transporting materials for construction on rough terrain. How did indigenous buildings traditionally respond to these conditions?

The primary criteria any house had to satisfy was to be sturdy and resilient and maintain a comfortable indoor climate. While the natural response in hot climates was to orient away from the sun, in cold climates it was to get the most out of the sun. Lower floors that would be cooler were used for storage and livestock, while upper floors were used for living. Balconies and terraces became important living spaces on sunny days. However, the hills are not a monolith, and different regions have their unique responses to local conditions.

Many indigenous houses of Himachal Pradesh use wood and stone in a distinct local technique called Kath Kuni (Kath meaning wood, and Kuni, corner). The wood (usually, local Deodar wood) is laid in long horizontal layers, alternating with layers of stone. No mortar or nails are used, and the strength of the building comes from these horizontal beams, rather than vertical supports like columns and pillars. This was to safeguard buildings against earthquakes.

Vertical members are more prone to buckling during tremors, explains Rahul Bhushan, a Himachal-based architect working on reviving the Kath Kuni technique. With the horizontal supports, the house might shake but would not collapse. The technique has been around for several hundred years, helping protect generations from earthquakes.

Kath Kuni houses were often built with an air gap between two layers of the wall. Air is a bad conductor, i.e. it doesn’t allow heat to pass through. So this helps retain warmth indoors.  Sloped roofs with slate helped drain rainwater, and interior walls were plastered with mud. The outer façade was left exposed, giving Kath Kuni buildings their distinctive beautiful aesthetic.

Another technique in this region was the Dhajji Dewari. This used a crisscrossing system of wooden posts, filled in with stone. The Dhajji technique is also resistant to earthquakes and is used in mountainous regions of South Asia like Kashmir and Pakistan.

It might appear that techniques like this would only suit small, low-rise buildings and would be impractical for the present. But the tallest Kath Kuni structure in Himachal is more than 12 storeys high, and built without any mortar. Called Chehni Kothi, it used to be a fort, and it is believed to have been built in the early 17th Century.